If you are complaining about champion diversity at worlds, here is why, the short version.
You play Solo Q, arguably, any champion can carry in Solo Q.
They play co-ordinated 5v5 games, in which champions KITS, that word, kits, THERE KITS, have a huge impact on the game, so only a select few champions, with certain kits, in certain team comps, will see play.
Size doesn't mean everything :(